Folate-encoded and Fe₃O₄-loaded polymeric micelles for dual targeting of cancer cells

Diblock copolymers of poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) bearing a tumor-targeting ligand, folate, were self-assembled into micelles. Superparamagnetic iron oxide (SPIO) nanoparticles and an anticancer drug doxorubicin (DOX) were coencapsulated within the micelles less than 100 nm in diameters. These SPIO-DOX-loaded micelles were superparamagnetic at room temperature, but turned ferrimagnetic at 10 K, consistent with magnetic properties of primary SPIO nanoparticles. Cell culture experiments demonstrated the potential of these polymeric micelles as an effective dual targeting nanoplatform for the delivery of anticancer drugs. Folate attachment to micelles resulted in the recognition of the micelles by tumor cells over-expressing folate receptors, leading to facilitation in cellular uptake of micelles, and the transport efficiency of the SPIO-loaded and folate-functionalized micelles into the tumor cells can be further enhanced by applying an external magnetic field to the cells.